Orally administered drugs are generally useful if the medication is effective when absorbed from the stomach and/or small intestine. Thus, conventional digestible carriers are useful for those medicaments. However, once the carrier is broken down by digestion, a drug cannot be delivered further. This makes treatment of the lower GI tract with orally administered drugs in standard digestible carriers substantially ineffective.
Accordingly, treatment of the large intestine and rectum is usually accomplished by anal exposure, e.g., enemas, suppositories, etc. This represents a clear disadvantage in terms of convenience to the patient.
The prior art has many examples of substances that are digestible being used as drug carriers. In particular, the use of glycerin and certain of its derivatives is known in the art.
U.S. Pat. No. 2,976,251 (Brokaw and Lyman, 1961) discloses the use of a high purity monoglyceride composition in gel form to be used as a carrier material for medicaments such as vitamins, amines, enzymes, hormones, and the like.
U.S. Pat. No. 3,536,816 (Kellner, 1970) teaches the use of a water-in-oil emulsion as a vehicle for pharmaceuticals. Kellner discloses gels, creams, and ointments for topical application to the skin.
U.S. Pat. No. 3,772,446 (Larsson, 1973) discloses an ointment base formulated with an .alpha.-monoglyceride of a C.sub.12-18 fatty acid. This formulation is also usable for topical application.
U.S. Pat. No. 4,305,936 (Klein, 1981) discloses a ointment type medicament that utilizes a glycerol ester of a fatty acid as a carrier.
U.S. Pat. No. 4,316,902 (Yu, et al., 1982) discloses an anhydrous base for medicaments composed of isopropyl myristate or isopropyl palmitate combined with glycerol monostearate.
None of the prior art found addresses the problem of providing a drug vehicle that can carry medicaments to the lower GI tract.
It is clear that the pharmaceutical field could make significant use of carriers that are non-digestible, non-toxic, and suitable for both topical and ingestible drug delivery.
It is among the objects of this invention to provide improved pharmaceutical formulations employing non-allergenic, non-digestible, non-toxic esterified alkoxylated polyols (EAPs) as carriers, bases or vehicles.
It is another object of this invention to provide esterified propoxylated glycerols suitable for use as non-toxic, non-irritating, non-digestible, and non-allergenic carriers for medicaments.
The recitation of such objects is not limitative of the scope of the subject matter of this invention. Still further and other objects will be evident from the specification and claims of this application.